/* 
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;

namespace Lucene.Net.Index
{
    
    sealed class SegmentMergeInfo : IDisposable
    {
        internal Term term;
        internal int base_Renamed;
        internal int ord; // the position of the segment in a MultiReader
        internal TermEnum termEnum;
        internal IndexReader reader;
        internal int delCount;
        private TermPositions postings; // use getPositions()
        private int[] docMap; // use getDocMap()

        private bool isDisposed;
        
        internal SegmentMergeInfo(int b, TermEnum te, IndexReader r)
        {
            base_Renamed = b;
            reader = r;
            termEnum = te;
            term = te.Term;
        }
        
        // maps around deleted docs
        internal int[] GetDocMap()
        {
            if (docMap == null)
            {
                delCount = 0;
                // build array which maps document numbers around deletions 
                if (reader.HasDeletions)
                {
                    int maxDoc = reader.MaxDoc;
                    docMap = new int[maxDoc];
                    int j = 0;
                    for (int i = 0; i < maxDoc; i++)
                    {
                        if (reader.IsDeleted(i))
                        {
                            delCount++;
                            docMap[i] = - 1;
                        }
                        else
                            docMap[i] = j++;
                    }
                }
            }
            return docMap;
        }
        
        internal TermPositions GetPositions()
        {
            if (postings == null)
            {
                postings = reader.TermPositions();
            }
            return postings;
        }
        
        internal bool Next()
        {
            if (termEnum.Next())
            {
                term = termEnum.Term;
                return true;
            }
            else
            {
                term = null;
                return false;
            }
        }

        public void Dispose()
        {
            if (isDisposed) return;

            // Move to protected method if class becomes unsealed
            termEnum.Close();
            if (postings != null)
            {
                postings.Close();
            }

            isDisposed = true;
        }
    }
}